1. Field of the Invention
The invention relates to the field of electric switches and specifically to normally open switches which incorporate a deflectable spring which is delfected by a manually depressible actuator from a normal position into engagement with contacts to close an electric circuit through the switch. These switches are well adapted for low priced units designed to be used in the keyboards of such hand-held devices as miniature electric calculators, addind machines, inventory input devices, etc. as well as in larger keyboard applications.
2. Description of the Prior Art
Computers, calculators, simple miniaturized adding machines and related data processing equipment have generated a vast number of uses for miniaturized switches. These switches must permit assembly of a multitude of such switches in keyboard arrangements where the keys or push buttons of the assembled switches, through internal electric circuits, carry out the computer, adding or data processing operation. Certainly, the cost of these keyboards, particularly in miniature and low cost equipment, to a large extent involves the cost of the multiple electric switches required for the keyboard.
Solid state adding machines and calculators, both desk type models and small pocket size adding machines or calculators, present a sizeable demand for keyboards employing miniaturized electric switches where depression of the keys or push bottons of the switches determines the carrying out of the required functions in the adding machine or calculator. Thus, the switches in closing circuits upon depression of their push buttons generate the requisite electrical signals for computers, calculators, pocket adding machines etc. to perform their output duties.
Numerous switch constructions have been developed for keyboards such as mentioned above. Such switch designs have ranged from mechanical-electrical proposals through elaborate electronic switching concepts. Considering the criticality of cost as a factor in keyboard construction, low initial investment, maintenance free operation and high operational reliability are prime requirements, but collectively they are difficult to achieve in miniaturized switches.